Implantable electrical stimulation devices have proven therapeutic in a variety of diseases and disorders. For example, pacemakers and implantable cardiac defibrillators have proven effective in the treatment of cardiac conditions. Spinal cord stimulation systems have been used as a therapeutic modality for the treatment of chronic pain syndromes. Deep brain stimulation has also been useful for treating refractory chronic pain syndromes and has been applied to treat movement disorders and epilepsy. Peripheral nerve stimulation has been used to treat chronic pain syndrome and incontinence, with a number of other applications under investigation. Functional electrical stimulation systems have been applied to restore some functionality to paralyzed extremities in spinal cord injury patients.
One disadvantage of these devices is that the electrode lead may migrate within the body. Migration may result in failure of the therapy or cause unwanted side effects. For example, some nerves are located next to or within muscles that may cause movement of the lead or catheter. Actuation of limbs may exert unequal pressures which can also cause migration.
The problem of migration may be particularly severe in cases of leads having a single electrode contact. Once the electrode contact has migrated away from its intended location in close proximity to its nerve target, the patient may have to use much higher electrical stimulation amplitudes to stimulate the nerve. In so doing, the patient may over stimulate the nerve endings resulting in pain and possibly even unwanted contraction of underlying muscle. In addition to these undesirable effects, the increased distance between the electrode contact and the nerve target may also result in an increase in the frequency the patient may have to charge the stimulation device to meet the energy demands of the higher amplitudes. This combination of side effects, painful skin over stimulation, undesirable muscle spasms, and/or frequent charging of the stimulation device may result in disuse of the therapy by the patient. Therefore, it is with respect to these considerations and others that the present invention has been made.